In the manufacturing process of glass articles, such as by the blow-blow process, a gob of molten glass is fed to each one of the machine's sections, for example of the I.S. type which forms a pre-form of the container or parison in an inverted position, and also forms the container crown. The preform is then inverted to its normal position and placed in a blow mold, where it receives a final air blowing, thus shaping the container to the desired final shape.
Once the final blowing has taken place, a take-out mechanism then transfers the container from the blow mold to a cooling plate where the container receives an initial cooling. Later, the container is transported on an endless moving belt to a glass annealing lehr.
Take-out mechanism used in I.S. glass forming machines are well known and essentially include an arm that is pivotally supported at one of its ends on a supporting structure which is placed at the front of the machine, and which is moved so that it oscillates angularly from the position of the finishing mold to the position of the cooling plate. A tong head assembly is supported at the end of the oscillating arm and moves in a relationship that is dependent to the oscillatory movement of the said arm, and supports at least a pair of tongs which are located at the lower extreme end of the tong head. A mechanism is provided for simultaneously opening and closing the tong assembly.
Although known take-out mechanisms operate more or less efficiently, they can cause a defect at the neck of the blown article due to differences in position of the vertical axis of the tongs and the vertical axis of the blow mold.
The defects appearing on the articles is caused at the time the tongs close. If variation exists between the axes, one of the halves of the tongs will contact the article before the other, and in so doing will push the container laterally, at which time the glass that is still in a hot state.
The ideal is that the tongs close without contacting the glass, and, that contact with the glass takes place after the ascending movement of the mechanism starts. However, it is very difficult to make the required adjustment between the tongs and the center of the blow mold.
Consequently, the take-out mechanisms of the prior art leave much to be desired, since it is not possible to adjust them accurately and it is not easy to eliminate lack of proper alignment between the blow mold and the tongs.